<template>
  <div class="top">
    <el-button type="primary" @click="handleProjection">动态投影转换</el-button>
  </div>
  <div class="mapBox">
    <div class="map" id="map1">
      <div class="title">投影坐标系（EPSG:3857）</div>
    </div>
    <div class="map" id="map2">
      <div class="title">投影坐标系（ESRI:53009）</div>
    </div>
  </div>
</template>

<script  setup>
import { onMounted, onBeforeUnmount } from "vue";
import { Map, View, Graticule } from "ol";
import { Tile as TileLayer, Vector as VectorLayer } from "ol/layer";
import { defaults, FullScreen } from "ol/control";
import { XYZ, Vector as VectorSource } from "ol/source";
import { GeoJSON } from "ol/format";
import { ATTRIBUTIONS } from "../../constants";
import { get, Projection } from "ol/proj";
import { register } from "ol/proj/proj4";
import proj4 from "proj4";
let map = null;
let transformMap = null;
const geojsonUrl = "/geojson/countries.geojson";
//定义球形摩尔魏特投影坐标系，对应ESRI的编号为ESRI:53009
proj4.defs(
  "ESRI:53009",
  "+proj=moll +lon_0=0 +x_0=0 +y_0=0 +a=6371000 " +
    "+b=6371000 +units=m +no_defs",
);
register(proj4);
const sphereMollweideProjection = new Projection({
  code: "ESRI:53009", //编号
  extent: [
    -9009954.605703328,
    -9009954.605703328,
    9009954.605703328,
    9009954.605703328,
  ], //范围
  worldExtent: [-179, -90, 179, 90], //世界经纬度范围
});
const vectLayer = new VectorLayer({
  source: new VectorSource({
    url: geojsonUrl,
    format: new GeoJSON(),
    wrapX: false,
  }),
});
const initMap = () => {
  map = new Map({
    //初始化map
    target: "map1",
    //地图容器中加载的图层
    layers: [
      new TileLayer({
        source: new XYZ({
          //   attributions: ATTRIBUTIONS,
          url:
            "http://t0.tianditu.com/DataServer?T=vec_w&x={x}&y={y}&l={z}&tk=3bc6874f2b919aa581635abab7759a3f",
          wrapX: false,
        }),
      }),
      vectLayer,
      new TileLayer({
        source: new XYZ({
          //   attributions: ATTRIBUTIONS,
          url:
            "http://t0.tianditu.com/DataServer?T=cva_w&x={x}&y={y}&l={z}&tk=3bc6874f2b919aa581635abab7759a3f",
          wrapX: false,
        }),
      }),
    ],
    view: new View({
      projection: get("EPSG:3857"), // 坐标系，有EPSG:4326和EPSG:3857
      center: [0, 0], // 深圳坐标
      //地图初始显示级别
      zoom: 1,
    }),
    //加载控件到地图容器中
    controls: defaults().extend([
      new FullScreen(), //加载全屏显示控件（目前支持非IE内核浏览器）
    ]),
  });
};
// 开始投影转换
const handleProjection = () => {
  transformMap = new Map({
    layers: [
      new VectorLayer({
        source: new VectorSource({
          url: geojsonUrl,
          format: new GeoJSON(),
        }),
      }),
    ],
    target: "map2",
    view: new View({
      projection: sphereMollweideProjection, //投影坐标系
      center: [120, 40],
      zoom: 1,
    }),
  });
};
onMounted(() => {
  initMap();
});
onBeforeUnmount(() => {
  if (map) {
    map.dispose();
    map = null;
  }
  if (transformMap) {
    transformMap.dispose();
    transformMap = null;
  }
});
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style lang='scss' scoped>
.top {
  height: 50px;
  line-height: 50px;
  text-align: center;
}
.mapBox {
  height: 830px;
  display: flex;
  justify-content: space-around;
  flex-direction: column;
  padding: 20px;
  box-sizing: border-box;
}
.map {
  position: relative;
  width: 80%;
  height: 48%;
  border: 2px dashed red;
  box-shadow: 0 0 10px #000;
  margin: 0 auto;
}
.title {
  width: 200px;
  position: absolute;
  bottom: 10px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1;
  color: red;
  text-align: center;
}
</style>